package com.custom.session;

import com.custom.executor.SimpleExecutor;
import com.custom.executor.SqlCommandType;
import com.custom.pojo.Configuration;
import com.custom.pojo.MappedStatement;

import java.beans.IntrospectionException;
import java.lang.reflect.*;
import java.sql.SQLException;
import java.util.List;

public class DefaultSqlSession implements SqlSession {
    private Configuration configuration;

    public DefaultSqlSession(Configuration configuration) {
        this.configuration = configuration;
    }

    @Override
    public <E> List<E> selectList(String statementId, Object... params) throws IllegalAccessException, IntrospectionException, InstantiationException, NoSuchFieldException, SQLException, InvocationTargetException, ClassNotFoundException {
        SimpleExecutor simpleExecutor=new SimpleExecutor();
        MappedStatement mappedStatement=configuration.getMappedStatementMap().get(statementId);
        List<Object> list=simpleExecutor.query(configuration,mappedStatement,params);
        return (List<E>) list;
    }

    @Override
    public <T> T selectOne(String statementId, Object... params) throws IllegalAccessException, ClassNotFoundException, IntrospectionException, InstantiationException, SQLException, InvocationTargetException, NoSuchFieldException {
        List<Object> objects=selectList(statementId,params);
        if(objects.size()==1){
            return (T) objects.get(0);
        }else {
            throw new RuntimeException("查询结果为空或者返回结果过多");
        }
    }

    @Override
    public <T> T getMapper(Class<T> mapperClass) {
        Object proxyInstance= Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                String methodName = method.getName();
                String className = method.getDeclaringClass().getName();
                String statementId = className + "." + methodName;
                MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementId);
                SqlCommandType sqlCommandType= mappedStatement.getSqlCommandType();
                if(sqlCommandType==SqlCommandType.SELECT){
                    Type genericReturnType = method.getGenericReturnType();
                    // 判断是否进行了 泛型类型参数化
                    if(genericReturnType instanceof ParameterizedType){
                        List<Object> objects = selectList(statementId, args);
                        return objects;
                    }
                    return selectOne(statementId,args);
                }else if(sqlCommandType==SqlCommandType.INSERT){
                    return insert(statementId, args);
                }else if(sqlCommandType==SqlCommandType.UPDATE){
                    return update(statementId, args);
                }else if(sqlCommandType==SqlCommandType.DELETE){
                    return delete(statementId,args);
                }else {
                    throw new RuntimeException("sql语句错误");
                }

            }
        });
        return (T) proxyInstance;
    }

    @Override
    public int insert(String statementId, Object... params) throws Exception {
        return update(statementId, params);
    }

    @Override
    public int update(String statementId, Object... params) throws Exception {
        SimpleExecutor simpleExecutor=new SimpleExecutor();
        MappedStatement mappedStatement=configuration.getMappedStatementMap().get(statementId);
        return simpleExecutor.update(configuration, mappedStatement, params);
    }

    @Override
    public int delete(String statementId, Object... params) throws Exception {
        return update(statementId, params);
    }
}
